In the second-round encounter played at Arthur Ashe Stadium on Wednesday evening, three-time champion Djokovic fought off a valiant effort from Juan Ignacio Londero to notch a 6-4, 7-6, 6-1 victory that was anything but easy.

Djokovic awaits the winner between fellow Serb Dusan Lajovic and American Denis Kudla.

In the other match, Federer shook off a slow start and clawed back from one set down to notch up a 3-6, 6-2, 6-3, 6-4 victory against Damir Dzumhur from Bosnia and Herzegovina.

The Swiss, competing in his 100th US Open match, was once again made to work hard, having also dropped the opening set in his first-round clash on Monday against Indian qualifier Sumit Nagal.

Next up for the third seed is No. 25 seed Lucas Pouille of France or Daniel Evans of Britain. Federer is 2-0 against both men in their respective head-to-head records and hasn’t dropped a set to either player.